Display apparatus and method of displaying

ABSTRACT

A display apparatus includes a plurality of housings connected by adjustable device for setting spacing between centers of the plurality of housings, each housing including: first image source mounted to side of housing; second image source mounted to housing angularly offset from first image source, wherein second image source includes higher resolution and narrower image field of view than first image source; optical combiner positioned in housing between first and second image sources, on which first image from first image source and second image from second image source are superimposed and made visible to user&#39;s eye; magnification lens for magnifying second image to increase image field of view; eyepiece lens for reducing focal distance between the optical combiner and the user&#39;s eye; and controller configured to control output of second image source to render colors to compensate for distortion and chromatic aberrations introduced by magnification lens.

TECHNICAL FIELD

The present disclosure relates generally to display apparatuses; andmore specifically, to display apparatuses comprising housings, saidhousings comprising image sources, optical combiners, magnificationlenses, eyepiece lenses and controllers. Moreover, the presentdisclosure also relates to methods of displaying via the aforementioneddisplay apparatuses.

BACKGROUND

Nowadays, several technologies (for example, such as virtual reality,augmented reality, and the like) are being developed for presenting asimulated environment to a user. Such technologies provide the user witha feeling of complete involvement (namely, immersion) within thesimulated environment by employing techniques such as stereoscopy. As aresult, when the user views the simulated environment, he/she isprovided with an enhanced perception of reality around him/her.Moreover, such simulated environments relate to fully virtualenvironments (namely, virtual reality environments) as well as realworld environments including virtual objects therein (for example, suchas augmented reality environments, mixed reality environments, and thelike).

Typically, the user uses a specialized device (for example, such as avirtual reality device, an augmented reality device, a mixed realitydevice, and the like) for viewing such simulated environments.Generally, the specialized device displays different views of a givenimage on separate display optics for both eyes of the user. As a result,the user is able to perceive stereoscopic depth within the given image.Examples of the specialized devices include virtual reality headsets, apair of virtual reality glasses, augmented reality headsets, a pair ofaugmented reality glasses, mixed reality headsets, a pair of mixedreality glasses, and the like.

However, conventional specialized devices have certain limitationsassociated therewith. Firstly, the specialized devices contain a largenumber of components having different shapes, sizes and functionalities.For proper functioning thereof, certain components are required to bearranged at certain specific positions or within specific regions of thespecialized device. Secondly, an optical path of light as it travelswithin such specialized devices is complex and depends on an arrangementof the components within the display apparatus. These requirements posedesign constraints on the specialized devices. Nowadays, somespecialized devices are designed to be large in size, in order toprovide ample space for accommodating their components. However, suchlarge sized specialized devices are often bulky and cumbersome to use.Alternatively, some specialized devices are designed to be small insize. In such small sized specialized devices, accommodating suchcomponents within the specialized devices is challenging due to spacelimitations and/or optical path requirements.

Therefore, in light of the foregoing discussion, there exists a need toovercome the aforementioned drawbacks associated with withinconventional specialized devices.

SUMMARY

The present disclosure seeks to provide a display apparatus. The presentdisclosure also seeks to provide a method of displaying using a displayapparatus having a plurality of housings. The present disclosure seeksto provide a solution to the existing problem of complex arrangement ofcomponents and bulkiness associated with conventional displayapparatuses. An aim of the present disclosure is to provide a solutionthat overcomes at least partially the problems encountered in prior art,and provides a compact display apparatus having a simple arrangement ofcomponents.

In one aspect, an embodiment of the present disclosure provides adisplay apparatus comprising:

-   a plurality of housings connected by an adjustable device for    setting a spacing between centers of the plurality of housings, each    of the housings comprising:-   a first image source mounted to a side of the housing;-   a second image source mounted to the housing angularly offset from    the first image source, wherein the second image source comprises a    higher resolution and a narrower image field of view than the first    image source;-   an optical combiner positioned in the housing between the first and    second image sources, on which a first image from the first image    source and a second image from the second image source are    superimposed and made visible to a user's eye;-   a magnification lens for magnifying the second image to increase the    image field of view, wherein the magnification lens is attached to    the housing between the second image source and the optical    combiner;-   an eyepiece lens for reducing a focal distance between the optical    combiner and the user's eye, wherein the eyepiece lens is mounted to    a side of the housing opposite the first image source, wherein the    eyepiece lens is interposed between the optical combiner and the    user's eye; and-   a controller configured to control an output of the second image    source to render colors to compensate for distortion and chromatic    aberrations introduced by the magnification lens.

In another aspect, an embodiment of the present disclosure provides amethod of displaying using a display apparatus having a plurality ofhousings, the method comprising:

-   connecting the plurality of housings by an adjustable device for    setting a spacing between centers of the plurality of housings;-   within each housing:-   using an optical combiner to:-   superimpose a first image from a first image source mounted to a    side of the housing, and a second image from a second image source    mounted to the housing angularly offset from the first image source;    and-   make visible to a user's eye the superimposed first and second    images, wherein the second image source comprises a higher    resolution and a narrower image field of view than the first image    source;-   using a magnification lens, attached to the housing between the    second image source and the optical combiner, to magnify the second    image to increase the image field of view;-   using an eyepiece lens, mounted to a side of the housing, opposite    the first image source and interposed between the optical combiner    and the user's eye, to reduce a focal distance between the optical    combiner and the user's eye; and-   using a controller to control an output of the second image source    to render colors to compensate for distortion and chromatic    aberrations introduced by the magnification lens.

Embodiments of the present disclosure substantially eliminate or atleast partially address the aforementioned problems in the prior art,and provides a display apparatus having a user-friendly size and properarrangement of components.

dditional aspects, advantages, features and objects of the presentdisclosure would be made apparent from the drawings and the detaileddescription of the illustrative embodiments construed in conjunctionwith the appended claims that follow.

It will be appreciated that features of the present disclosure aresusceptible to being combined in various combinations without departingfrom the scope of the present disclosure as defined by the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The summary above, as well as the following detailed description ofillustrative embodiments, is better understood when read in conjunctionwith the appended drawings. For the purpose of illustrating the presentdisclosure, exemplary constructions of the disclosure are shown in thedrawings. However, the present disclosure is not limited to specificmethods and instrumentalities disclosed herein. Moreover, those skilledin the art will understand that the drawings are not to scale. Whereverpossible, like elements have been indicated by identical numbers.

Embodiments of the present disclosure will now be described, by way ofexample only, with reference to the following diagrams wherein:

FIG. 1 illustrates a schematic view of a display apparatus, inaccordance with an embodiment of the present disclosure;

FIG. 2 illustrates a sectional view of a given housing, in accordancewith an embodiment of the present disclosure; and

FIG. 3 illustrates steps of a method of displaying using a displayapparatus, in accordance with an embodiment of the present disclosure.

In the accompanying drawings, an underlined number is employed torepresent an item over which the underlined number is positioned or anitem to which the underlined number is adjacent. A non-underlined numberrelates to an item identified by a line linking the non-underlinednumber to the item. When a number is non-underlined and accompanied byan associated arrow, the non-underlined number is used to identify ageneral item at which the arrow is pointing.

DETAILED DESCRIPTION OF EMBODIMENTS

The following detailed description illustrates embodiments of thepresent disclosure and ways in which they can be implemented. Althoughsome modes of carrying out the present disclosure have been disclosed,those skilled in the art would recognize that other embodiments forcarrying out or practising the present disclosure are also possible.

In one aspect, an embodiment of the present disclosure provides adisplay apparatus comprising:

-   a plurality of housings connected by an adjustable device for    setting a spacing between centers of the plurality of housings, each    of the housings comprising:-   a first image source mounted to a side of the housing;-   a second image source mounted to the housing angularly offset from    the first image source, wherein the second image source comprises a    higher resolution and a narrower image field of view than the first    image source;-   an optical combiner positioned in the housing between the first and    second image sources, on which a first image from the first image    source and a second image from the second image source are    superimposed and made visible to a user's eye;-   a magnification lens for magnifying the second image to increase the    image field of view, wherein the magnification lens is attached to    the housing between the second image source and the optical    combiner;-   an eyepiece lens for reducing a focal distance between the optical    combiner and the user's eye, wherein the eyepiece lens is mounted to    a side of the housing opposite the first image source, wherein the    eyepiece lens is interposed between the optical combiner and the    user's eye; and-   a controller configured to control an output of the second image    source to render colors to compensate for distortion and chromatic    aberrations introduced by the magnification lens.

In another aspect, an embodiment of the present disclosure provides amethod of displaying using a display apparatus having a plurality ofhousings, the method comprising:

-   connecting the plurality of housings by an adjustable device for    setting a spacing between centers of the plurality of housings;-   within each housing:-   using an optical combiner to:-   superimpose a first image from a first image source mounted to a    side of the housing, and a second image from a second image source    mounted to the housing angularly offset from the first image source;    and-   make visible to a user's eye the superimposed first and second    images, wherein the second image source comprises a higher    resolution and a narrower image field of view than the first image    source;-   using a magnification lens, attached to the housing between the    second image source and the optical combiner, to magnify the second    image to increase the image field of view;-   using an eyepiece lens, mounted to a side of the housing, opposite    the first image source and interposed between the optical combiner    and the user's eye, to reduce a focal distance between the optical    combiner and the user's eye; and-   using a controller to control an output of the second image source    to render colors to compensate for distortion and chromatic    aberrations introduced by the magnification lens.

The present disclosure provides the aforementioned display apparatus andthe aforementioned method of displaying using such a display apparatus.The display apparatus described herein has a simple arrangement ofcomponents within the display apparatus. Notably, the described displayapparatus includes few, small-sized components which are properlyaccommodated at suitable positions within the display apparatus. Thedescribed arrangement and specifications of such components allow fordisplaying a visual scene of a simulated environment to the user of thedisplay apparatus when the display apparatus is used by the user.Furthermore, the aforesaid display apparatus is user friendly since itis compact and lightweight.

Throughout the present disclosure, the term “display apparatus” refersto specialized equipment that is configured to present a simulatedenvironment to the user when the display apparatus, in operation, isworn by the user on his/her head. In such an instance, the displayapparatus acts as a device (for example, such as a virtual realityheadset, a pair of virtual reality glasses, an augmented realityheadset, a pair of augmented reality glasses, a mixed reality headset, apair of mixed reality glasses, and so forth) that is operable to presenta visual scene of the simulated environment to the user. The displayapparatus may also commonly be referred to as “head-mounted displayapparatus”.

The display apparatus comprises the plurality of housings. Throughoutthe present disclosure, the term “housing” refers to an outer coveringthat encloses and protects various components of the display apparatus.Beneficially, the plurality of housings protects such components fromany damage caused by dust, heat and the like.

The plurality of housings are connected by the adjustable device.Notably, the adjustable device is employed for setting the spacingbetween centers of the plurality of the housings. In other words, theadjustable device is employed for adjusting (namely, increasing ordecreasing) the spacing between the centers of the plurality ofhousings, as per requirement. Therefore, a space is created between theplurality of housings to accommodate various components. Each of theplurality of housings comprises the first image source, the second imagesource, the optical combiner, the magnification lens, the eyepiece lensand the controller.

It will be appreciated that the space created between centers theplurality of housings when joined together forms an internal region toaccommodate various components therein. Such an internal region may alsocommonly be referred to as an “optical chamber”.

In an exemplary implementation, the display apparatus comprises oneoptical chamber per eye of the user. In such a case, separate opticalchambers for a left eye and a right eye of the user are formed in thedisplay apparatus. When the display apparatus comprises separatecomponents (for example, such as the first image source and the secondimage source) for the left eye and the right eye, such separate opticalchambers enclose said separate components. As an example, separate firstimages and separate second images for the left eye and the right eye ofthe user may be displayed using separate first image sources andseparate second image sources for the left eye and the right eye,respectively. The separate first images for the left eye and the righteye collectively constitute the first image whereas the separate secondimages for the left eye and the right eye collectively constitute thesecond image.

In another exemplary implementation, the display apparatus comprises asingle optical chamber for both eyes of the user. In such a case, thesingle optical chamber encloses various components of the displayapparatus for both the left eye and the right eye on a shared basis. Asan example, the display apparatus may comprise a single first imagesource and a single second image source to be used for both eyes of theuser on a shared basis. The single first image source and the singlesecond image source are used to display a single first image and asingle second image for both the left eye and the right eye,respectively, on the shared basis.

Optionally, the optical chamber has a hole covered with Gore-Tex® orsimilar. Beneficially, the Gore-Tex® prevents dust from entering theoptical chamber. Furthermore, the Gore-Tex® allows controlled adjustmentof external air pressure.

Optionally, the adjustable device comprises a motorized threaded shaftconnected between the plurality of housings. Notably, the motorizedthreaded shaft mechanically couples the plurality of housings in amanner that the space is created between the plurality of housings. Theadjustable device moves the plurality of housings closer to or fartherfrom each other to adjust the spacing between the centers of theplurality of housings. In an example, the adjustable device may comprisea pair of rails and motorized screw for rotatably moving the pluralityof housings closer to or away from each other.

Throughout the present disclosure, the term “image source” refers toequipment that, when employed, renders a given image. Beneficially, agiven image source has a same resolution throughout its array of pixels.In other words, the given image source has a same pixel densitythroughout the entire array of pixels. When the given image is renderedvia the given image source, a projection of the given image emanatesfrom an image rendering surface of the given image source.

Throughout the present disclosure, the term “projection of the givenimage” refers to a collection of light rays emanating from a given imagesource when the given image is rendered thereat. The projection of thegiven image (namely, the collection of light rays) may transmit throughand/or reflect from the optical element and various other components ofthe display apparatus before reaching the user's eye. For purposes ofembodiments of the present disclosure, the term “projection of the givenimage” has been used consistently, irrespective of whether thecollection of light rays is transmitted or reflected.

The first image source is mounted to the side of the housing and thesecond image source is mounted to the housing angularly offset from thefirst image source. In other words, the first and second image sourcesare arranged in a manner that the second image source is positioned at agiven angle from the first image source. Notably, the second imagesource is arranged in a manner that a center of gravity of thehead-mounted display apparatus is close to a head of the user when thedisplay apparatus, in operation, is worn by the user on his/her head. Insuch a case, the second image source is positioned towards the eyepiecelens.

Optionally, the first image source and/or the second image source is/areimplemented as a display. Optionally, the display is selected from thegroup consisting of: a Liquid Crystal Display (LCD), a Light EmittingDiode (LED)-based display, an Organic LED (OLED)-based display, a microOLED-based display, a Liquid Crystal on Silicon (LCoS)-based display,and a Cathode Ray Tube (CRT)-based display.

Optionally, the first image source and/or the second image source is/areimplemented as a projector and a projection screen associated therewith.Optionally, the projector is selected from the group consisting of: anLCD-based projector, an LED-based projector, an OLED-based projector, anLCoS-based projector, a Digital Light Processing (DLP)®-based projector,and a laser projector.

It will be appreciated that the first image source is employed to renderthe first image thereon and the second image source is employed torender the second image thereon. Notably, the first image and the secondimage collectively constitute an input image depicting the visual scenethat is to be presented to the user, via the display apparatus.Therefore, the “first image” and the “second image” can be understood tocorrespond to a first portion and a second portion of the input image,respectively.

Optionally, the first image corresponds to an entirety of the inputimage whereas the second image corresponds to a specific portion of theinput image. In other words, a size (namely, dimensions) of the secondimage is smaller as compared to a size (namely, dimensions) of the firstimage. Therefore, dimensions of the first image source are larger ascompared to dimensions of the second image source.

Optionally, the sizes of the first image source and the second imagesource are measured as a diagonal dimension of the first image sourceand the second image source, respectively. Notably, the diagonaldimension of a given image source is measured as a distance between twodiagonal points (namely, two diagonal corners) of the given imagesource.

Optionally, the first image source has the diagonal dimension of betweenapproximately 2 and 4 inches. In other words, the diagonal dimension ofthe first image source lies in a range of 2 inches to 4 inches. Forexample, the diagonal dimension of the first image source may be from 2,2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6 or 3.8 inches up to 2.2, 2.4, 2.6,2.8, 3, 3.2, 3.4, 3.6, 3.8 or 4 inches. In an example implementation,the first image source may have the diagonal dimension of 3.2 inches.

Alternatively, optionally, the first image source has the diagonaldimension of approximately lesser than 2 inches or greater than 4inches. In other words, the diagonal dimension of the first image sourceis lesser than 2 inches or greater than 4 inches. In an example, thediagonal dimension of the first image source may be 1, 1.2, 1.4, 1.6,1.8 or 2 inches. In another example, the diagonal dimension of the firstimage source may be 4, 4.2, 4.4, 4.6, 4.8, 5, 5.2, 5.4, 5.6, 5.8 or 6inches.

Optionally, the second image source has the diagonal dimension ofbetween approximately 0.5 and 1.5 inches. In other words, the diagonaldimension of the second image source lies in a range of 0.5 inches to1.5 inches. For example, the diagonal dimension of the second imagesource may be from 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.3 or 1.4 inches upto 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.3, 1.4 or 1.5 inches. In an exampleimplementation, the second image source may have the diagonal dimensionof 0.7 inches.

Alternatively, optionally, the second image source has the diagonaldimension of approximately greater than 1.5 inches. In other words, thediagonal dimension of the second image source is greater than 1.5inches. In an example, the diagonal dimension of the second image sourcemay be 1.5, 1.6, 1.7, 1.8, 1.9 or 2 inches.

As mentioned previously, the second image source comprises the higherresolution and the narrower field of view than the first image source.In other words, the second image source acts as a high-resolution imagesource as compared to the first image source which acts as alow-resolution image source. Therefore, the second image (rendered bythe second image source) relates to a high-resolution representation ofthe second portion of the input image and the first image (rendered bythe first image source) relates to a low-resolution representation ofthe input image.

Throughout the present disclosure, the term “resolution” of a givenimage source refers to a display resolution of the given image source.Notably, the display resolution of the given image source refers topixel density (namely, pixels per unit area) within the given imagesource. It will be appreciated that an image resolution of a given imageis same as the resolution of the given image source by which said givenimage is rendered. The term “image resolution” refers to a detail that agiven image holds. The image resolution is typically measured as thenumber of pixel values per unit area associated with a given image.

Optionally, the first image source has a resolution of betweenapproximately 0.5 and 5.0 megapixels. In other words, the resolution ofthe first image source lies in a range of 0.5 megapixels to 5.0megapixels. More optionally, the first image source has the resolutionof between approximately 1.2 and 3.2 megapixels. In other words, moreoptionally, the resolution of the first image source lies in a range of1.2 megapixels to 3.2 megapixels. For example, the resolution of thefirst image source may be from 0.5, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2,2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6 or 4.8megapixels up to 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8,3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8 or 5 megapixels. In anexample implementation, the first image source may have the resolutionof 2 megapixels.

Optionally, the first image source has a resolution of approximately1600×1200 pixels. In such a case, the first image source has aresolution of approximately 1.92 megapixels. Furthermore, such an imagesource has a 4:3 aspect ratio.

Alternatively, optionally, the first image source has a resolution ofapproximately 960×720 pixels, 1024×768 pixels, 1280×960 pixels,1400×1050 pixels, 1440×1080 pixels, 1856×1392 pixels, 1920×1440 pixels,or 2048×1536 pixels.

Optionally, the second image source has a resolution of approximately1920×1080 pixels. In such a case, the second image source has aresolution of approximately 2.07 megapixels. Furthermore, such an imagesource has a 16:9 aspect ratio.

Alternatively, optionally, the second image source has a resolution ofapproximately 2560×1440 pixels or 3840×2160 pixels.

Optionally, the second image source has a 10 micrometer pixel size and a3 micrometer sub-pixel size. The term “pixel size” refers to a size ofpixels of a given image source. Notably, the pixel size of the givenimage source is measured as distance between diagonal vertices of pixelsof the given image source. Notably, each pixel of the given image sourcecomprises a plurality of sub-pixels. In an example, each pixel may havethree sub-pixels arranged either vertically (namely, one on top of theother) or horizontally (namely, one next to the other).

Optionally, the first image source and the second image source have aPenTile® arrangement of the pixels. In an example, the PenTile®arrangement of the pixels follows a RGBG layout. In such an example, thenumber of green sub-pixels is twice the number of blue sub-pixels aswell as twice the number of red sub-pixels. In particular, the number ofgreen sub-pixels is equal to a total number of blue and red sub-pixels.Beneficially, such an arrangement of the pixels leverages opticalproperties of human vision which is more sensitive to green color fordisplaying the first and second images. In another example, the PenTile®arrangement of the pixels follows a RGBW layout. Beneficially, in suchan arrangement of the pixels, white pixels enhance brightness of therendered image, thereby reducing an overall power required forprojection of said image of a given brightness.

Throughout the present disclosure, the term “image field of view” refersto an angular extent of a given image source that, in operation, rendersa given image. An angular extent of the given image rendered by thegiven image source is generally equal to the image field of view of thegiven image source. Notably, the field of view of each eye of the useris approximately about 115 degrees. Beneficially, the image sourceshaving the field of view approximately equivalent to the user's eyesprovide the user with a greater feeling of immersion and betterawareness of the simulated environment.

In an embodiment, the first image source has a wide image field of viewas compared to the second image source. In such a case, an angular widthof the first image (rendered at the first image source) is greater thanan angular width of the second image (rendered at the second imagesource). Herein, the term “angular width” refers to an angular width(namely, an angular extent) of a given image with respect to theperspective of the user's eye, namely with respect to a centre of theuser's gaze. It will be appreciated that since the projection of thefirst image is to be incident upon the retina of the user's eye whereasthe projection of the second image is to be incident upon the fovea ofthe user's eye, the first image source has the wide image field of viewas compared to the second image source.

Optionally, the first image source has an image field of view of betweenapproximately 70 to 140 degrees. In other words, a horizontal andvertical image field of view of the first image source lies in a rangeof 70 degrees to 140 degrees. In such a case, the angular width of thefirst image lies in a range of 70 degrees to 140 degrees. For example,the image field of view dimension of the first image source may be from70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130 or 135 degreesup to 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135 or 140degrees.

Optionally, the second image source has an image field of view ofbetween approximately 15 to 45 degrees. In other words, a horizontal andvertical image field of view of the second image source lies in a rangeof 15 degrees to 45 degrees. In such a case, the angular width of thesecond image lies in a range of 15 degrees to 45 degrees. For example,the image field of view of the second image source may be from 15, 16,17, 18, 19, 20, 21, 22, 23, 24 25, 26, 27, 28, 29, 30, 31, 32, 33, 34,35, 36, 37, 38, 39, 40, 41, 42, 43 or 44 degrees up to 16, 17, 18, 19,20, 21, 22, 23, 24 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37,38, 39, 40, 41, 42, 43, 44 or 45 degrees.

The optical combiner is positioned in the housing between the first andsecond image sources, on which the first image from the first imagesource and the second image from the second image source aresuperimposed and made visible to the user's eye. Throughout the presentdisclosure, the term “optical combiner” refers to equipment (forexample, such as optical components) for optically combining theprojection of the first image with the projection of the second image.In operation, the optical combiner optically combines the projection ofthe first image with the projection of the second image to constitute acombined projection, wherein the combined projection is a projection ofthe input image depicting the visual scene. When the display apparatusis worn and used by the user, the combined projection is incident uponthe user's eye for displaying the visual scene to the user.

It will be appreciated that optical properties of the optical combinerallow for such optical combination of the first image and the secondimage. In some implementations, the optical combiner is implemented byway of a single optical component. In other implementations, the opticalcombiner is implemented by way of a plurality of optical components.

Optionally, the optical combiner is implemented by way of at least oneof: a lens, a mirror, a beam splitter, a semi-transparent mirror, asemi-transparent film, a prism, an optical waveguide, a polarizer.

Optionally, the optical combiner comprises a silver-coated,semi-transparent glass mirror. Beneficially, the silver coating on theglass mirror provides a high reflectivity surface for the glass mirror,thereby providing reflective optical properties of the optical combiner.Furthermore, such mirror construction provides reflectance value that issubstantially independent of the angle of the incoming light. In anexample, the silver-coated, semi-transparent glass mirror may have areflectivity of 25 percent, and a transmission (namely, transmissivity)of 70 percent. In another example the silver-coating of the mirror isfurther deposited with silicon dioxide (SiO₂).

Furthermore optionally, the glass mirror is coated with ananti-reflective coating at a back surface of the glass mirror.

Optionally, the optical combiner comprises a semi-transparent mirrorhaving a reflectivity of between approximately 10 to 60 percent, and atransmission of between approximately 85 to 40 percent. In other words,the reflectivity of the semi-transparent mirror lies in a range of 10percent to 60 percent and the transmission (namely, transmissivity) liesin a range of 85 percent to 40 percent. The term “reflectivity” refersto ability of a given surface to reflect the light and the term“transmission” refers to ability of a given surface to pass (namely,transmit) the light therethrough. In an example, the semi-transparentmirror can be manufactured using a glass or plastic plate covered with areflective metal coating or di-electric coating. For example, thesemi-transparent mirror may have the reflectivity of between 10, 15, 20,25, 30, 35, 40, 45, 50 or 55 percent up to 15, 20, 25, 30, 35, 40, 45,50, 55 or 60 percent and the transmission of between 85, 80, 75, 70, 65,60, 55, 50 or 45 percent up to 80, 75, 70, 65, 60, 55, 50, 45 or 40percent.

In an embodiment, the semi-transparent mirror allows for combining twooptical paths of the projections of the first and second images into asingle optical path. In an example, the semi-transparent mirror maycomprise a substantially-transmissive surface and asubstantially-reflective surface opposite to thesubstantially-transmissive surface, the substantially-reflective surfaceobliquely facing the eyepiece lens, wherein the semi-transparent mirroris arranged in a manner that the projection of the first image entersthrough the substantially-transmissive surface and passes through thesubstantially-reflective surface towards the eyepiece lens, whilst theprojection of the second image reflects from thesubstantially-reflective surface towards the eyepiece lens. It will beappreciated that the substantially-reflective surface of thesemi-transparent mirror obliquely faces the eyepiece lens in a mannerthat the projection of the second image completely passes through theeyepiece lens, upon reflection from the substantially-reflectivesurface. By “substantially-transmissive” and “substantially-reflective”,it is meant that a given surface has transmissivity and reflectivitythat lies in a range of 60 percent to 95 percent, and more optionally,in a range of 75 percent to 90 percent, respectively.

Optionally, the optical combiner is positioned in the housing atapproximately 35 to 50 degrees with respect to a surface of the first orsecond image source. For example, the optical combiner can be positionedin the housing at approximately 35, 36, 37, 38, 39, 40, 41, 42, 43, 44,45, 46, 47, 48 or 49 degrees up to 36, 37, 38, 39, 40, 41, 42, 43, 44,45, 46, 47, 48, 49 or 50 degrees with respect to the surface of thefirst or second image source. As an example, the optical combiner may bepositioned at an angle of 45 degrees with respect to an image renderingsurface of the first image source, and may be positioned at an angle of40 degrees with respect to an image rendering surface of second imagesource.

Optionally, the optical combiner is positioned at a focal distance fromthe magnification lens. In other words, a distance between the opticalcombiner and the magnification lens is approximately equal to a focallength of the magnification lens.

The magnification lens is used for magnifying the second image toincrease the image field of view, wherein the magnification lens isattached to the housing between the second image source and the opticalcombiner. Notably, the magnification lens is arranged on the opticalpath of the projection of the second image, such that a desiredmagnification of the second image is achieved when the projection of thesecond image passes through said magnification lens. In such a case, themagnification lens can be understood to increase an apparent image fieldof view of the second image source. In an example, the magnificationlens may be implemented using a plano-convex lens. In another example,the magnification lens may be implemented using a bi-convex lens.

Optionally, the magnification lens magnifies a size (namely, the angularwidth) of the second image. In such a case, the magnification lensenlarges the projection of the second image in a manner that a size ofthe second image that is visible to the user is greater than a size ofthe second image rendered by the second image source. Therefore, themagnification lens increases the apparent image field of view of thesecond image source. The magnification lens is manufactured using glass,plastic, or any other suitable material.

Optionally, a length of the optical path of the projection of the secondimage lies within a range of 1 metre to 1.5 metres. In other words, theoptical distance travelled by the projection of the second image(notably, from the second image source to the user's eye, via themagnification lens and the optical combiner) lies within the range of 1metre to 1.5 metres. For example, the length of the optical path of theprojection of the second image may be from 1, 1.1, 1.2, 1.3 or 1.4metres up to 1.1, 1.2, 1.3, 1.4 or 1.5 metres.

Optionally, the magnification lens is arranged in a proximity of thesecond image source. Such an arrangement of the magnification lens andthe second image source allows the second image to appear sharp to theuser for a wide range of optical path length of the projection of thesecond image. In an embodiment, the magnification lens is attached tothe housing in a manner that said magnification lens is arranged on topof the second image source. In such a case, the magnification lens isairtightly mounted on the top of the second image source, therebypreventing dust from entering therebetween. In another embodiment, themagnification lens is attached to the housing in a manner that saidmagnification lens is arranged at a specific distance (for example, fewmillimeters) from the image rendering surface of the second imagesource. Optionally, in this regard, the distance between themagnification lens and the image rendering surface of the second imagesource lies in a range of 0.5 millimeters to 5 millimeters. For example,the magnification lens can be arranged at a distance of 0.5, 1.0, 1.5,2.0, 2.5, 3.0, 3.5, 4.0 or 4.5 millimeters up to 1.0, 1.5, 2.0, 2.5,3.0, 3.5, 4.0, 4.5 or 5.0 millimeters from the image rendering surfaceof the second image source. As an example, the magnification lens may bearranged at a distance of 2 millimeters from the image rendering surfaceof the second image source.

Optionally, the magnification lens enlarges the field of view to betweenapproximately 15 to 45 degrees. In other words, the magnification lensenlarges a horizontal and vertical field of view in a range of 15degrees to 45 degrees.

Notably, in such a case, the image field of view of the second imagesource is lesser than 45 degrees, and can be enlarged by themagnification lens to lie between approximately 15 to 45 degrees. Forexample, the magnification lens can enlarge the field of view from 15,16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33,34, 35, 36, 37, 38, 39, 40, 41, 42, 43 or 44 degrees up to 16, 17, 18,19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36,37, 38, 39, 40, 41, 42, 43, 44 or 45 degrees.

As an example, the image field of view of the second image source may beequal to 10 degrees. The magnification lens may increase said imagefield of view to 30 degrees. As a result, the second image rendered atthe second image source appears to have an angular width of 30 degrees.

As another example, the image field of view of the second image sourcemay be equal to 20 degrees. The magnification lens may increase saidimage field of view to 40 degrees. As a result, the second imagerendered at the second image source appears to have an angular width of40 degrees.

Optionally, the magnification lens has a minimum refractive index ofapproximately 1.5. Optionally, the magnification lens has a refractiveindex of between approximately 1.5 to 2. For example, the magnificationlens may have the refractive index from 1.5, 1.55, 1.6, 1.65, 1.7, 1.75,1.8, 1.85, 1.9 or 1.95 up to 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9,1.95 or 2.

Optionally, the magnification lens has a magnification of betweenapproximately 1.2 to 1.6. In other words, the magnification of themagnification lens lies in a range of 1.2 to 1.6. For example, themagnification lens may have the magnification of between approximately1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5 or 1.55 up to 1.25, 1.3, 1.35, 1.4,1.45, 1.5, 1.55 or 1.6. In an example implementation, the magnificationlens may have the magnification of 1.5. In another exampleimplementation, the magnification lens may have the magnification of1.25.

Furthermore, optionally, a length of the optical path of the projectionof the first image lies within a range of 1 metre to 1.5 metres. Forexample, the length of the optical path of the projection of the firstimage may be from 1, 1.1, 1.2, 1.3 or 1.4 metres up to 1.1, 1.2, 1.3,1.4 or 1.5 metres.

Each of the housings comprises the eyepiece lens. Throughout the presentdisclosure, the term “eyepiece lens” refers to an optical componentconfigured to direct the combined projection including the projectionsof the first and second images, towards the user's eye, when the displayapparatus is worn by the user. The eyepiece lens is mounted to the sideof the housing that is opposite to the first image source, wherein theeyepiece lens is interposed between the optical combiner and the user'seye. The eyepiece lens faces the image rendering surface of the firstimage source.

Optionally, the eyepiece lens enables user's eyes to focus on closeproximity in a distance of between approximately 30 to 80 mm. In otherwords, the eyepiece lens enables user's eyes to focus on close proximityin the distance in a range of 30 mm to 80 mm. In particular, theeyepiece lens enables the user's eyes to focus on the first image sourcethat lies in the distance of between approximately 30 to 80 mm from theeyepiece lens. As a result, the eyepiece lens reduces the focal distancebetween the optical combiner and the user's eye. Due to opticalproperties of the eyepiece lens, an optical distance traveled by theprojection of the first image from the first image source to the user'seye is increased. As a result, a physical distance between the user'seye and the first image source is reduced. For example, the eyepiecelens enables user's eyes to focus on close proximity in distance ofbetween approximately 30, 35, 40, 45, 50, 55, 60, 65, 70 or 75 mm to 35,40, 45, 50, 55, 60, 65, 70, 75 or 80 mm. Therefore, a distance betweenthe eyepiece lens and the first image source lies between approximately30, 35, 40, 45, 50, 55, 60, 65, 70 or 75 mm to 35, 40, 45, 50, 55, 60,65, 70, 75 or 80 mm.

Optionally, the eyepiece lens is arranged in a manner that the firstimage source is arranged at a suitable position within the plurality ofhousings, thereby allowing the user to view the first image (rendered atthe first image source) without any optical distortion. The first imagesource has the wide image field of view of between approximately 70degrees to 140 degrees with respect to the perspective of the user'seye. Notably, the eyepiece lens allows the first image having such largeangular width to be seen properly, even from the close physical distancebetween the user's eyes and the first image source.

Optionally, the eyepiece lens receives the projection of the first imageand the projection of the second image and modifies the optical pathand/or optical characteristics of the aforesaid projections, whilstdirecting the aforesaid projections towards the user's eye. In oneexample, the eyepiece lens may magnify a size (or angular dimensions) ofthe projection of the first image. In such an example, use of themagnifying eyepiece lens allows for use of a dimensionally small firstimage source within the display apparatus.

In an embodiment, the eyepiece lens is an injection molded plastic lensmanufactured using an optical quality plastic. In another embodiment,the eyepiece lens is a glass lens manufactured using an optical qualityglass.

Furthermore, optionally, the eyepiece lens is implemented by way of atleast one of: a convex lens, a plano-convex lens, a Liquid Crystal (LC)lens, a liquid lens, a Fresnel lens, aspherical lens, achromatic lens.

Optionally, the eyepiece lens provides the focal distance of betweenapproximately 25 to 100 mm. In other words, the focal distance of theeyepiece lens lies in a range of 25 mm to 100 mm. Specifically, theeyepiece lens provides the focal distance between the first image sourceand the user's eye in a range of 25 mm to 100 mm. For example, theeyepiece lens may provide the focal distance of between approximately25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 or 95 mm to 30,35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or 100 mm.

Optionally, the eyepiece lens has a diameter of between approximately 30to 70 mm. In other words, the diameter of the eyepiece lens lies in arange of 30 mm to 70 mm. It will be appreciated that the diameter of theeyepiece is selected to be one that allows the combined projection(which comprises the projection of the first image and the projection ofthe second image) to properly pass therethrough. For example, theeyepiece lens may have the diameter of between approximately 30, 35, 40,45, 50, 55, 60 or 65 mm to 35, 40, 45, 50, 55, 60, 65 or 70 mm.

Optionally, the eyepiece lens has a thickness of between approximately 8to 10 mm. In other words, the thickness of the eyepiece lens lies in arange of 8 mm to 10 mm. For example, the eyepiece lens may have thethickness of between approximately 8, 8.1, 8.2, 8.3, 8.5, 8.6, 8.8, 8.9,9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8 or 9.9 mm to 8.1, 8.2, 8.3,8.5, 8.6, 8.8, 8.9, 9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9 or 10mm.

The controller is configured to control the output of the second imagesource to render colors to compensate for distortion and chromaticaberrations introduced by the magnification lens. The controller isimplemented by way of hardware, software, firmware or a combination ofthese, for controlling the output of the second image source. Generally,the projection of the second image would undergo a certain degree ofdistortion and chromatic aberration upon passing though themagnification lens, due to optical properties of the magnifying lens.When such a projection would be incident upon the user's eyes, thedistortions and color irregularities in the second image would bevisible to the user. In order to compensate for such an unfavorablescenario, the controller is configured to adjust colors of the secondimage at a time of rendering the second image. Therefore, acolor-compensated second image is rendered at the second image source.As a result, when the projection of such a color-compensated secondimage passes through the magnification lens towards the user's eyes, theuser views a second image that is free from distortions and chromaticaberrations.

Optionally, the controller is configured to process the second image byemploying at least one image processing operation. The controllercontrols the output of the second image source to render colors by wayof such processing of the second image. Optionally, the at least oneimage processing operation is selected from the group consisting of:image sharpening, low pass filtering, color processing, gammacorrection, and edge processing.

Optionally, the display apparatus further comprises means for detectinggaze direction, and the controller is coupled in communication with themeans for detecting a gaze direction.

Throughout the present disclosure, the term “means for detecting thegaze direction” refers to specialized equipment for detecting and/ortracking the gaze direction of the user. Such specialized equipment arewell known in the art. For example, the means for detecting the gazedirection can be implemented using contact lenses with sensors, camerasmonitoring a position of a pupil of the user's eye, infrared (IR) lightsources and IR cameras, a bright pupil-detection equipment, a darkpupil-detection equipment and the like. Beneficially, said means isarranged in a manner that it does not cause any obstruction in theuser's view.

It will be appreciated that said means is employed to detect the gazedirection of the user repeatedly over a period of time, when the displayapparatus in operation is worn by the user. Since the controller iscoupled to the means for detecting the gaze direction of the user, thecontroller is configured to receive, from said means, informationindicative of the detected gaze direction of the user. Optionally, thecontroller or the image source is configured to generate the first andsecond images, based upon an instantaneous gaze direction of the userdetected during operation, in real-time or near real-time.

Optionally, the means for detecting gaze direction is to be employed todetect the gaze direction of the user's eye, for enabling the projectionof the second image to be incident upon and around the fovea of theuser's eye and for enabling the projection of the first image to beincident upon a retina of the user's eye, of which the fovea is just asmall part. Therefore, even upon a change in the gaze direction (namely,due to a movement of the user's eye), the second image is projected onand around the fovea and the first image is projected on the retina, forimplementing active foveation in the display apparatus.

Optionally, the means for detecting gaze direction comprises a pluralityof eye-illuminating light sources for emitting light to illuminate theuser's eye, and an eye-tracking camera for capturing an image of theuser's eye and reflections of the emitted light from the user's eye.Optionally, in this regard, the controller is configured to process theimage to detect the gaze direction of the user based upon a relativeposition of a pupil of the user's eye with respect to the reflections ofthe emitted light. Optionally, when processing the image, the controlleris configured to differentiate said reflections of the emitted lightfrom visual artifacts.

Optionally, each of the housings further comprises the eye-trackingcamera mounted to the housing proximate the second image source. In anexemplary implementation, the eye-tracking camera is positioned besidethe second image source. In such a case, the second image source and theeye-tracking camera are arranged in a manner that the second imagesource and the eye-tracking camera are angularly offset from theeyepiece lens, wherein the eyepiece lens is positioned in front of theuser's eye. Optionally, in this regard, the projection of the secondimage is reflected from the optical combiner towards the eyepiece lens,and the reflections of the emitted light from the user's eye arereflected by the optical combiner towards the eye-tracking camera.Beneficially, the eye-tracking camera is to be positioned in front ofthe user's eye, thereby allowing for accurate detection of the gazedirection of the user for implementing gaze contingency via the displayapparatus. When the eye-tracking camera is positioned in front of theuser's eye, the light emitted by the plurality of eye-illuminating lightsources falls directly upon the user's eye without being obstructed byeyelashes of the user.

Optionally, the controller is further configured to control themotorized threaded shaft in response to an output from the eye-trackingcamera to adjust the spacing between the centers of the plurality ofhousings to correspond to an interpupillary distance of the user.Notably, the controller allows for an automatic adjustment of thespacing between the centers of the plurality of housings. When the gazedirection of the user changes, the relative position of the pupils ofthe user's eyes also changes. This results in a change in theinterpupillary distance of the user. If the spacing between the centersof the plurality of housings is not adjusted according to theinterpupillary distance of the user, the arrangement of the plurality ofhousings with respect to the user's eyes is improper. At such improperarrangement, the visual scene appears misaligned to the user. Therefore,the controller controls the motorized threaded shaft to adjust thespacing between the centers of the plurality of housings with respect tothe change in the interpupillary distance of the user. This allows forthe display apparatus to display a perfectly aligned visual scene to theuser, thereby enhancing the user's experience of the simulatedenvironment.

It will be appreciated that the spacing between the centers of theplurality of housings is to be adjusted corresponding to a currentinterpupillary distance of the user, based upon the detected gazedirection of the user, for implementing active foveation in the displayapparatus. In such a case, the projections of the second imagecorresponding to the left and the right eyes of the user are correctlyincident upon fovea of the left and the right eyes of the user,respectively. In an example, the spacing between the centers of theplurality of housings may be adjusted by employing a pair of rails andmotorized screw, thereby allowing movement of the plurality of housings.Beneficially, such a movement of the plurality of housings compensatesfor varying interpupillary distance of the user based upon the detectedgaze direction of the user.

Optionally, each of the housings further comprises the plurality ofeye-illuminating light sources mounted to the housing proximate theeyepiece lens. More optionally, the plurality of eye-illuminating lightsources are positioned in a manner that the plurality ofeye-illuminating light sources are arranged either on a periphery of theeyepiece lens or are adjacent to the eyepiece lens. It will beappreciated that such an arrangement of the eye-illuminating lightsources allows for minimal obstruction in the optical path between theeye-illuminating light sources and the user's eye.

The term “eye-illuminating light sources” refers to light sourcesconfigured to emit light of a specific wavelength. Optionally, theplurality of eye-illuminating light sources are configured to emit lightof infrared or near-infrared wavelength. The emitted light of infraredor near-infrared wavelength are invisible to the human eye, thereby,reducing unwanted distraction when such light is incident upon theuser's eye. Alternatively, optionally, the plurality of eye-illuminatinglight sources are configured to emit light of a wavelength withinvisible spectrum.

Optionally, the plurality of eye-illuminating light sources areimplemented by way of at least one of: infrared light emitting diodes,infrared lasers, infrared light projectors, infrared displays, visiblelight emitting diodes, visible light lasers, visible light projectors,visible light displays.

It will be appreciated that the plurality of eye-illuminating lightsources are arranged near the user's eye such that the light emitted bythe plurality of eye-illuminating light sources are incident upon theuser's eye. For example, such light may be incident upon the cornea ofthe user's eye. In such an instance, the emitted light is reflected froman outer surface of the cornea of the user's eye, thereby constitutingcorneal reflections (namely, glints) in the user's eye.

Optionally, the plurality of eye-illuminating light sources have aspecific shape. In such a case, a reflection of the light emitted fromsuch eye-illuminating light sources can be easily identified in capturedimage. Notably, a given glint in the captured image can be identified tobe a reflection of the plurality of eye-illuminating light sources, whenthe shape of the given glint is similar to the specific shape of theeye-illuminating light sources. Alternatively, the given glint in thecaptured image can be identified to be a visual artifact, when the shapeof the given glint is different the specific shape of theeye-illuminating light sources.

Furthermore, optionally, the controller is configured to determine whichreflection in the captured image corresponds to which eye-illuminatinglight source based on the specific shape of said eye-illuminating lightsource. In such a case, the controller is configured to map shape,rotational orientation and position of a given glint to shape,rotational orientation and position of the plurality of eye-illuminatinglight sources.

In an example implementation, the plurality of eye-illuminating lightsources may be implemented using six infrared light sources having aV-shape.

Furthermore, the six infrared light sources may have differentorientations (for example such as <, >, v, {circumflex over ( )} and thelike).

Optionally, the controller is configured to receive the input image anduse the detected gaze direction to determine a region of visual accuracyof the input image. In an example, the input image may be received froman imaging device (for example, such as a digital camera) coupled to thedisplay apparatus. In such a case, the imaging device may capture animage of a real-world environment as the input image to be projectedonto the eye. The “region of visual accuracy of the input image” refersto a region of the input image whereat the detected gaze direction ofthe eye is focused. In another example, the input image may be receivedfrom a memory unit communicably coupled to the controller. Specifically,the memory unit may be configured to store the input image in a suitableformat including, but not limited to, Joint Photographic Experts Group(JPEG), Tagged Image File Format (TIFF), Portable Network Graphics(PNG), Graphics Interchange Format (GIF), and Bitmap file format (BMP).

Optionally, the controller is configured to process the input image togenerate the first image and the second image in a manner that

-   -   the first image corresponds to an entirety of the input image,    -   the second image corresponds to the region of visual accuracy of        the input image, and    -   a region of the first image that corresponds to the region of        visual accuracy of the input image is masked.

Optionally, at the optical combiner, the first and second images areoptically combined in a manner that the projection of the second imagesubstantially overlaps the projection of the masked region of the firstimage. Hereinabove, by “substantially overlaps”, it is meant that amisalignment between corresponding pixels of the second image and thepixels of the masked region of the first image lies within a range of 0to 10 pixels, and more optionally, within a range of 0 to 5 pixels.

Optionally, when the region of the first image that corresponds to theregion of visual accuracy of the input image is masked, the region ofthe first image that corresponds to the second image is masked. Suchmasking is performed for example, by dimming or darkening correspondingpixels of the first image.

It will be appreciated that the projection of the second imagesubstantially overlaps with the projection of the masked region of thefirst image to avoid distortion of the region of visual accuracy of theinput image. Specifically, the region of visual accuracy of the inputimage is represented within both, the first image of low resolution andthe second image of high resolution. The overlap (or superimposition) ofprojections of low and high-resolution images of a same region wouldresult in distortion of appearance of the same region. The second imagecontains more visual detail pertaining to the region of visual accuracyof the input image, as compared to the first image. Therefore, theregion of the first image that substantially corresponds to the regionof visual accuracy of the input image is masked, in order to project thehigh-resolution second image without distortion towards the user's eyes.

Optionally, the controller is configured to control the optical combinerto optically combine the projections of the first and second images.Optionally, in this regard, the controller is configured to adjust aposition and/or an orientation of the optical combiner, via at least oneactuator, in a manner that the projection of the second imagesubstantially overlaps the projection of the masked region of the firstimage.

Additionally or alternatively, optionally, the controller is configuredto adjust a position and/or an orientation of the first image sourceand/or the second image source, via at least one actuator, in a mannerthat the projection of the second image substantially overlaps theprojection of the masked region of the first image.

Throughout the present disclosure, the term “actuator” refers toequipment (for example, such as electrical components, mechanicalcomponents, magnetic components, polymeric components, and so forth)that is employed to adjust position and/or orientation of a givencomponent of the display apparatus.

Optionally, the first image and the second image are renderedsubstantially simultaneously. By “substantially simultaneously”, it ismeant that a time instant of rendering the first image and a timeinstant of rendering the second image lie within 200 milliseconds ofeach other, and more optionally, within 20 milliseconds of each other.

Optionally, the controller is configured to control the output of thefirst image source by performing at least one image processingoperation. Optionally, in this regard, the at least one image processingoperation may be implemented prior to or whilst rendering the firstimage.

The present disclosure also relates to the method as described above.Various embodiments and variants disclosed above apply mutatis mutandisto the method.

Optionally, the method further comprises using the eye-tracking cameramounted to the housing proximate the second image source to trackmovements of the user's eye.

Optionally, in the method, the adjustable device comprises the motorizedthreaded shaft connected between the plurality of housings, and whereinthe method further comprises using the controller to control themotorized threaded shaft in response to the output from the eye-trackingcamera to adjust the spacing between the centers of the plurality ofhousings to correspond to the interpupillary distance of the user.

Optionally, the method further comprises using the plurality ofeye-illuminating light sources mounted to the housing proximate theeyepiece lens to illuminate the user's eye.

Optionally, in the method, the first image source has the resolution ofbetween approximately 0.5 and 5.0 megapixels.

Optionally, in the method, the first image source has the resolution ofapproximately 1600×1200 pixels.

Optionally, in the method, the first image source has the diagonaldimension of between approximately 2 and 4 inches.

Optionally, in the method, the first image source has the image field ofview of between approximately 70 to 140 degrees.

Optionally, in the method, the second image source has the resolution ofapproximately 1920×1080 pixels.

Optionally, in the method, the second image source has the 10 micrometerpixel size and the 3 micrometer sub-pixel size.

Optionally, in the method, the second image source has the diagonaldimension of between approximately 0.5 and 1.5 inches.

Optionally, in the method, the optical combiner comprises asilver-coated, semi-transparent glass mirror.

Optionally, in the method, the optical combiner comprises thesemi-transparent mirror having the reflectivity of between approximately10 to 60 percent, and the transmission of between approximately 85 to 40percent.

Optionally, the method further comprises positioning the opticalcombiner in each housing at approximately 35 to 50 degrees with respectto the surface of the first or second image source.

Optionally, the method further comprises using the magnification lens toenlarge the field of view to between approximately 15 to 45 degrees.

Optionally, in the method, the magnification lens has the minimumrefractive index of approximately 1.5.

Optionally, in the method, the magnification lens has the magnificationof between approximately 1.2 to 1.6.

Optionally, the method further comprises using the eyepiece lens toprovide the focal distance of between approximately 25 to 100 mm.

Optionally, in the method, the eyepiece lens has the diameter of betweenapproximately 30 to 70 mm.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1, illustrated is a schematic view of a displayapparatus, in accordance with an embodiment of the present disclosure.The display apparatus 100 comprises a plurality of housings (not shown)connected by an adjustable device (not shown) for setting a spacingbetween centers of the plurality of housings, wherein each of thehousings comprising a first image source 102, a second image source 104,an optical combiner 106, a magnification lens 108, an eyepiece lens 110and a controller (not shown). The first image source 102 is mounted to aside of the housing. The second image source 104 is mounted to thehousing angularly offset from the first image source 102. The secondimage source 104 comprises a higher resolution and a narrower imagefield of view than the first image source 102. The optical combiner 106is positioned in the housing in between the first image source 102 andsecond image source 104. On the optical combiner 106, a first image fromthe first image source 102 and a second image from the second imagesource 104 are superimposed and made visible to a user's eye. Themagnification lens 108 is configured for magnifying the second image toincrease the image field of view, wherein the magnification lens 108 ispositioned between the second image source 104 and the optical combiner106. The eyepiece lens 110 is mounted to a side of the housing oppositeto the first image source 102 for reducing a focal distance between theoptical combiner 106 and the user's eye, wherein the eyepiece lens 110is interposed between the optical combiner 106 and the user's eye. Thecontroller is configured to control an output of the second image source104 to render colors to compensate for distortion and chromaticaberrations introduced by the magnification lens 108.

As shown, ‘a’ denotes a diameter of the eyepiece lens 110 whereas ‘b’denotes a thickness of the eyepiece lens 110. Furthermore ‘c’ denotes adistance between the first image source 102 and the eyepiece lens 110.Moreover, ‘d’ denotes a distance between the second image source 104 andthe optical combiner 106 and ‘e’ denotes a distance between the opticalcombiner 106 and the eyepiece lens 110. As shown, ‘x’ denotes an anglebetween an optical axis of the second image source 104 and an opticalaxis of the optical combiner 106, ‘f’ denotes thickness of themagnification lens 108 and ‘g’ denotes an overall thickness of anarrangement of the second image source 104 and the magnification lens110. Furthermore, ‘i’ denotes a length (namely, a horizontal dimension)of the first image source 102 and ‘h’ is equal to half of the length‘i’.

Referring to FIG. 2, illustrated is a sectional view of a given housing202, in accordance with an embodiment of the present disclosure. Thegiven housing 202 comprises a first image source 204, a second imagesource 206, an optical combiner 208, a magnification lens 210, aneyepiece lens 212 and a controller (not shown). Furthermore, the givenhousing further comprises an eye-tracking camera 214 mounted to thehousing proximate the second image source 206.

Referring to FIG. 3, illustrated are steps of a method of displayingusing a display apparatus, in accordance with an embodiment of thepresent disclosure. The display apparatus has a plurality of housings.

At a step 302, the plurality of housings are connected by an adjustabledevice for setting a spacing between centers of the plurality ofhousings.

At a step 304, a first image from a first image source mounted to a sideof the housing, and a second image from a second image source mounted tothe housing angularly offset from the first image source aresuperimposed using an optical combiner. The superimposed first andsecond images are made visible to a user's eye, wherein the second imagesource comprises a higher resolution and a narrower image field of viewthan the first image source.

At a step 306, the second image is magnified, using a magnification lensattached to the housing between the second image source and the opticalcombiner, to increase the image field of view.

At a step 308, a focal distance between the optical combiner and theuser's eye is reduced, using an eyepiece lens mounted to a side of thehousing, opposite the first image source and interposed between theoptical combiner and the user's eye.

At a step 310, an output of the second image source is controlled usinga controller to render colors to compensate for distortion and chromaticaberrations introduced by the magnification lens.

The steps 302, 304, 306, 308, and 310 are only illustrative and otheralternatives can also be provided where one or more steps are added, oneor more steps are removed, or one or more steps are provided in adifferent sequence without departing from the scope of the claimsherein.

Modifications to embodiments of the present disclosure described in theforegoing are possible without departing from the scope of the presentdisclosure as defined by the accompanying claims. Expressions such as“including”, “comprising”, “incorporating”, “have”, “is” used todescribe and claim the present disclosure are intended to be construedin a non-exclusive manner, namely allowing for items, components orelements not explicitly described also to be present. Reference to thesingular is also to be construed to relate to the plural.

1. A display apparatus comprising: a plurality of housings connected byan adjustable device for setting a spacing between centers of theplurality of housings, each of the housings comprising: a first imagesource mounted to a side of the housing; a second image source mountedto the housing angularly offset from the first image source, wherein thesecond image source comprises a higher resolution and a narrower imagefield of view than the first image source; an optical combinerpositioned in the housing between the first and second image sources, onwhich a first image from the first image source and a second image fromthe second image source are superimposed and made visible to a user'seye; a magnification lens for magnifying the second image to increasethe image field of view, wherein the magnification lens is attached tothe housing between the second image source and the optical combiner; aneyepiece lens for reducing a focal distance between the optical combinerand the user's eye, wherein the eyepiece lens is mounted to a side ofthe housing opposite the first image source, wherein the eyepiece lensis interposed between the optical combiner and the user's eye; and acontroller configured to control an output of the second image source torender colors to compensate for distortion and chromatic aberrationsintroduced by the magnification lens.
 2. The display apparatus of claim1, wherein each of the housings further comprises an eye-tracking cameramounted to the housing proximate the second image source.
 3. The displayapparatus of claim 2, wherein the adjustable device comprises amotorized threaded shaft connected between the plurality of housings. 4.The display apparatus of claim 3, wherein the controller is furtherconfigured to control the motorized threaded shaft in response to anoutput from the eye-tracking camera to adjust the spacing between thecenters of the plurality of housings to correspond to an interpupillarydistance of the user.
 5. The display apparatus of claim 1, wherein eachof the housings further comprises a plurality of eye-illuminating lightsources mounted proximate the eyepiece lens.
 6. The display apparatus ofclaim 1, wherein the first image source has a resolution of betweenapproximately 0.5 and 5.0 megapixels.
 7. The display apparatus of claim1, wherein the first image source has a resolution of approximately1600×1200 pixels.
 8. The display apparatus of claim 1, wherein the firstimage source has a diagonal dimension of between approximately 2 and 4inches.
 9. The display apparatus of claim 1, wherein the first imagesource has an image field of view of between approximately 70 to 140degrees.
 10. The display apparatus of claim 1, wherein the second imagesource has a resolution of approximately 1920×1080 pixels.
 11. Thedisplay apparatus of claim 1, wherein the second image source has a 10micrometer pixel size and a 3 micrometer sub-pixel size.
 12. The displayapparatus of claim 1, wherein the second image source has a diagonaldimension of between approximately 0.5 and 1.5 inches.
 13. The displayapparatus of claim 1, wherein the optical combiner comprises asilver-coated, semi-transparent glass mirror.
 14. The display apparatusof claim 1, wherein the optical combiner comprises a semi-transparentmirror having a reflectivity of between approximately 10 to 60 percent,and a transmission of between approximately 85 to 40 percent.
 15. Thedisplay apparatus of claim 1, wherein the optical combiner is positionedin the housing at approximately 35 to 50 degrees with respect to asurface of the first or second image source.
 16. The display apparatusof claim 1, wherein the magnification lens enlarges the field of view tobetween approximately 15 to 45 degrees.
 17. The display apparatus ofclaim 1, wherein the magnification lens has a minimum refractive indexof approximately 1.5.
 18. The display apparatus of claim 1, wherein themagnification lens has a magnification of between approximately 1.2 to1.6.
 19. The display apparatus of claim 1, wherein the eyepiece lensprovides the focal distance of between approximately 25 to 100 mm. 20.The display apparatus of claim 1, wherein the eyepiece lens has adiameter of between approximately 30 to 70 mm.
 21. A method ofdisplaying using a display apparatus having a plurality of housings, themethod comprising: connecting the plurality of housings by an adjustabledevice for setting a spacing between centers of the plurality ofhousings; within each housing: using an optical combiner to: superimposea first image from a first image source mounted to a side of thehousing, and a second image from a second image source mounted to thehousing angularly offset from the first image source; and make visibleto a user's eye the superimposed first and second images, wherein thesecond image source comprises a higher resolution and a narrower imagefield of view than the first image source; using a magnification lens,attached to the housing between the second image source and the opticalcombiner, to magnify the second image to increase the image field ofview; using an eyepiece lens, mounted to a side of the housing, oppositethe first image source and interposed between the optical combiner andthe user's eye, to reduce a focal distance between the optical combinerand the user's eye; and using a controller to control an output of thesecond image source to render colors to compensate for distortion andchromatic aberrations introduced by the magnification lens.
 22. Themethod of claim 21, further comprising using an eye-tracking cameramounted to the housing proximate the second image source to trackmovements of the user's eye.
 23. The method of claim 21, wherein theadjustable device comprises a motorized threaded shaft connected betweenthe plurality of housings, and wherein the method further comprisesusing the controller to control the motorized threaded shaft in responseto an output from the eye-tracking camera to adjust the spacing betweenthe centers of the plurality of housings to correspond to aninterpupillary distance of the user.
 24. The method of claim 21, whereinthe method further comprises using a plurality of eye-illuminating lightsources mounted proximate the eyepiece lens to illuminate the user'seye.
 25. The method of claim 21, wherein the first image source has aresolution of between approximately 0.5 and 5.0 megapixels.
 26. Themethod of claim 21, wherein the first image source has a resolution ofapproximately 1600×1200 pixels.
 27. The method of claim 21, wherein thefirst image source has a diagonal dimension of between approximately 2and 4 inches.
 28. The method of claim 21, wherein the first image sourcehas an image field of view of between approximately 70 to 140 degrees.29. The method of claim 21, wherein the second image source has aresolution of approximately 1920×1080 pixels.
 30. The method of claim21, wherein the second image source has a 10 micrometer pixel size and a3 micrometer sub-pixel size.
 31. The method of claim 21, wherein thesecond image source has a diagonal dimension of between approximately0.5 and 1.5 inches.
 32. The method of claim 21, wherein the opticalcombiner comprises a silver-coated, semi-transparent glass mirror. 33.The method of claim 21, wherein the optical combiner comprises asemi-transparent mirror having a reflectivity of between approximately10 to 60 percent, and a transmission of between approximately 85 to 40percent.
 34. The method of claim 21, further comprising positioning theoptical combiner in each housing at approximately 35 to 50 degrees withrespect to a surface of the first or second image source.
 35. The methodof claim 21, further comprising using the magnification lens to enlargethe field of view to between approximately 15 to 45 degrees.
 36. Themethod of claim 21, wherein the magnification lens has a minimumrefractive index of approximately 1.5.
 37. The method of claim 21,wherein the magnification lens has a magnification of betweenapproximately 1.2 to 1.6.
 38. The method of claim 21, further comprisingusing the eyepiece lens to provide the focal distance of betweenapproximately −25 to 100 mm.
 39. The method of claim 21, wherein theeyepiece lens has a diameter of between approximately 30 to 70 mm.